Method of making buttons from plastic material



y 1937' w. M. DAVIDSON ET AL ,470

METHOD OF MAKING BUTTONS FROM PLASTIC MATERIAL Filed Feb. 17, 1954 I i J I l B g 1 j W ATTORNEY INVENTOR Patented July 20, 1937 UNITED STATES PATENT OFFICE DIETHOD OF MAKING BUTTONS FROM PLASTIC MATERIAL ware Application February 17, 1934, Serial No. 711,720 In Canada June 28, 1933 17 Claims.

The principal object of this invention is to produce at low cost buttons of excellent quality of any desirable shape or size, from plastic materials capable of being quickly hardened, and presenting a smooth finish, for example, the phenolformaldehyde plastics, the shellac plastics, the casein plastics, etc.

A further object is to devise a means of producing buttons from a plastic compressible material with smoothly finished thread holes moulded therein which will dispense with the difficult and expensive operation of boring the thread holes.

The principal feature of the invention consists in the novel method of compressing a plastic mass between a pair of dies, one of which is provided with rigid hole-forming studs and the other of which is provided with cavities registering with the studs to produce clearly defined portions which are readily frangible to separate them from the finished button.

A further important feature consists in the-formation of a retaining rib on the button which holds the button in one section of the die while the other section is withdrawn and which permits the ultimate removal of the button from the retaining die.

A still further feature of importance consists in the novel manner of removing the protuberances formed at the end of the thread holes and also removing the retaining flange and material excess fin from the perimeter of the button.

'In the accompanying drawing, Fig. 1 is an enlarged cross sectional view of a button constructed in accordance with this invention.

Fig. 2 is an underside plan view of the button as shown in Fig. 1.

Fig. 3 is a top plan.

Fig. 4 is a vertical mid-sectional view through the forming die showing the mould cavity therein.

Fig. 5 is a vertical mid-sectional view showing a means for removing the thread hole protuberances and also the means for removing the edge flange and fin from the button.

In carrying this present method into effect it is desirable to provide a multiple cavity die which may conveniently be accomplished by having a pair of plates bored with any desirable number of recesses to receive the die blocks l and 2 respectively. These are preferably arranged in a definite number ofrows and are secured in any desirable manner in a die plate.

The die I is here shown formed with 'a cavity 3 of Whatever contour may be desired to form one side of the button 4. A plurality of bevelled hobs 5 extend outwardly from the face of the die cavity 3 in correspondence with the location of the thread holes 6 of the button and form the chamfered or tapered entrance 6' to the button holes.

Holes 1 are bored in axial alignment with the hobs 5 and extend inwardly therefrom into the die block I and pins 8 are fitted therein, the lower ends thereof projecting beyond the hobs 5, being slightly tapered and terminating in the conical ends 9.

The die 2 is here shown formed with a cavity In of whatever contour may be required to form the opposite side ll of the button.

Arranged in axial alignment with each of the studs or punches 8 are conical shaped recesses l3. These are cut in the surface of the cavity ID of the die 2 and each recess is surrounded by a circular flange M which projects beyond the main surface of the cavity and is preferably provided with a flaring outer side l5 which forms a tapering countersink I6 in thebutton surrounding each of the thread holes.

A circular channel depression ll surrounds each of the flanges I4 which forms a smooth ridge l8 around each of the countersinks l6.

, The terminal ends of the punches 8 are of slightly smaller diameter than is the internal diameter of the recesses l3 and the punches extend into the recesses below the outer perimeters of the flanges l4 so that the plastic material from which the button is formed may flow around the ends of the punches filling the recesses l3.

The .die 2 is provided with a central orifice I9 extending therethrough through which a flanged knockout punch 20 extends. This punch is adapted to remove the finished buttons from the die.

The cavity I0 is formed with a narrow peripheral recess 2| preferably V-shaped in section, in the wall adjacent to the edge of the die. This recess forms a rib 22 on the button and holds the button securely in the die 2 while the die I is being withdrawn.

In the manufacture of the button the blank of plastic material is placed in the cavity of the lower die. This can be accomplished in any suitable manner. The two die members are then closed together as illustrated in Fig. 4. As the dies close together the punches 8 pierce the blank and force the plastic material into the cavities l3. The narrow space between the flanges l4 surrounding the cavities I3 and the inner ends of the punches 8 form a Very thin frangible wall 23 in the button structure.

The rest of the mold cavity fills up as the dies close together, the quantity of the material in the blank being suflicient to fill the mold when the ncessary pressure has been applied.

A slight fin is usually formed at the point of contact of the die members, but the rib 22 is formed in the die 2 adjacent to the parting line between the dies.

When the necessary pressure has been applied and the forming operation is completed, the dies are separated and as they move apart the tapered ends of the punches 8 are withdrawn from the thread holes, while the flange 22 maintains an engaging contact with the circular recess 2|, holding the button from being withdrawn from the die 2.

When the die members have been separated the knock-out member 20 is operated in a suitable manner to eject the formed button from the die 2, the button material being sufficiently flexible to permit the withdrawing of the rib 22 from the retaining groove under the pressure applied to the center.

The button as thus formed is provided with the tapered protuberances 24 supported on the thin frangible walls 23 and a slight pressure from the inside of the thread holes or a crushing pressure from the outer side of the button will break away these thin frangible walls, removing the protuberances, thus leaving the tapered countersinks l6 and the smooth flange It! as a smooth finish to the holes.

A very effective way of removing the protuberances 24 is found in the use of the device as illustrated in Fig. 5. The button is placed upona suitable holding member here shown in the form of a rotatable disc 25 suitably rotated by means of a central shaft 26 and 7 having surface 21 formed to f t the button. I

Pins 28 extend into the thread holes 6 and pro-' ject through the button a sufiicient distance to engage the inside of the protuberances 24 and break them off. 1

A finger 29 is shown arranged to hold the button in position while the pins are operating to effect the separation of the protuberances 24.

While the button is thus held in position the member 25 is rotated on its axis and the fin and rib 22 is brought into contact with a suitable abrasive or cutting member 30 which is operated in a suitable manner to remove the flange or fin.

The manufacture of buttons in accordance with a process such as described is extremely simple. The preformed plastic blank is dropped into the die; the die members are brought together applying pressure to form the button. When the forming operation is complete the button is removed from the die, placed upon a stripping element which removes the protuberances from the thread holes and simultaneously the edge is cleared of any obstruction and made perfectly smooth.

The button thus finished is strong and durable. The thread holes are smooth and will not cut the threads and they can be made in great variety and at very low cost.

We claim:

1. A method of making buttons consisting in placing a plastic blank within a die, forming tapered recesses for thread holes in one side of the blank and protuberances on the other side in alignment with said recesses, the walls of the protuberances being made thinner adjacent the body of the button than at other parts of the protuberances, removing the formed button from the die, breaking the thin walls of the protuberances from the button,-and smoothing the edges of the button.

2. A method of making buttons consisting in placing a plastic blank within a die, forcing perforating pins through said blank to form thread holes and compressing the plastic material around said pins to form a button and forming protuberances on the side of the button intended to lie against the material to which the button is to be fastened, and removing any surplus material including the protuberances.

3. In a method of making molded buttons, the steps of molding a mass of plastic material to the shape of the button body, molding recesses in the body for thread holes, molding protuberances extending from one face of the body closing the recesses and joined to the body by thin frangible walls at the junctures of the recesses, and breaking the walls to separate the protuberances from the body leaving the thread holes through the body.

4. In a method of making molded buttons, the steps of molding a mass of plastic material to the shape of the button body, molding recesses in the body for thread holes, molding protuberances extending from one face of the body and joined to the body by thin frangible walls at the junc tures of the recesses, molding countersinks surrounding said walls where the walls join the body, and breaking the walls within the countersinks to separate the protuberances from the body leaving thread holes through the body.

5. In a method of making molded buttons, the steps of molding a mass of plastic material to the shape of the button body, molding recesses in the 3 body for thread holes, molding protuberances extending from one face of the body, said protuberances having thin frangible walls joining the protuberances to the body and a central portion thicker than the walls, and applying pressure to the protuberances breaking the walls to separate the protuberances from the body.

6. In a method of making molded buttons, the steps of molding a mass of plastic material to the shape of the button body, molding recesses in the body for thread holes, molding protuberances extending from one face of the body and joined to the body by thin frangible walls at the junctures ofthe recesses, molding a protecting ridge extending from one face of the body spaced from said walls, and breaking the walls to separate the protuberances from the body whereby thread holes are formed and the broken edges of the walls are guarded by the protecting ridge.

7. In a method of making molded buttons, the steps 01 molding a mass of plastic material between separable die parts to the shape of the button body, molding'recesses in the body for thread holes, molding protuberances extending from a face of the body at the ends of the recesses and joined to the body by thin frangible connections at the junctures of the recesses, molding a ribon the body releasably to hold the button in one part of the die as the die parts are separated, ejecting the button from the die parts, breaking the frangible connections to separate the protuberances from the body leaving the thread holes and removing the rib.

8. As an article of manufacture, a molded button blank comprising a body of button shape, recesses in the body for thread holes, and protuberances extending from one side of the body closing the recesses and joined to the body by thin frangible walls at the juncture of the recesses and side of the body whereby the protuberances may easily be broken from the body.

9. As an article of manufacture, a. molded button blank comprising a body of button shape, recesses in the body for thread holes, protuberances extending from one side of the body and joined to the body by thin frangible walls at the junctures of the recesses and side of the body, and countersinks surrounding said junctures whereby the protuberances may easily be broken from the body at the bottom of the countersinks.

10. As an article of manufacture, a molded button blank comprising a body of button shape having a rear face designed to lie next to the surface to which the button will be fastened, recesses in the body for thread holes, and protuberances extending from the rear face of the body and joined to the body by thin frangible walls at the juncture of the recesses and rear face.

11. As an article of manufacture, a molded button blank comprising a body of button shape, recesses in the body for thread holes, protuberances extending from one side of the body and joined to the body by thin frangible walls at the junctures of the recesses and side of the body whereby the protuberances may be separated from the body by breaking the walls, and a protecting ridge extending from said side of the body a distance greater than said walls whereby the broken walls will be guarded.

12. As an article of manufacture, a molded button blank comprising a body of button shape, recesses in the body for thread holes, and protuberances extending from one side of the body, said protuberances having thin frangible walls joining the protuberances to the body and a central portion thicker than the walls whereby the walls may easily be broken to separate the protuberances from the body by pressure applied to said central portions.

13. As an article of manufacture, a molded button blank comprising a body of button shape, recesses extending through the body beyond the side thereof for thread holes, protuberances extending from one side of the body and-joined to the body by thin frangible walls at the junctures of the recesses and side of the body whereby the protuberances may easily be broken from the body to leave the thread holes.

14. A method of making buttons comprising placing a plastic blank within a die, forming protuberances on the side of the blank intended to lie against the material to which the button is to be fastened and forming recesses from the other side of the blank in alignment with said protuberances, the walls of the protuberances being made thinner adjacent the body of the button than at other parts of the protuberances, and breaking the thin walls of the protuberances to form thread holes.

15. A method of making buttons comprising placing a plastic blank within a die, forming recesses in one side of the blank and protuberances on the other side in alignment with said recesses, forming a smooth ridge on the body of the button blank around the walls of the protuberances, and breaking the walls of the protuberances below the ridge to form thread holes from the recesses leaving the ridge surrounding the broken parts of the walls.

16. A method of making buttons comprising placing a plastic blank within a die, forming recesses in one side of the blank and thin walled protuberances on the other side, the walls of said protuberances being in alignment with the walls of said recesses, and breaking the thin walls of the protuberances so that the line of break is non-parallel to the walls of the recesses thereby to form thread holes from the recesses with any rough edges resulting from the broken walls of the protuberances out of the path of threads passing through the thread holes.

17. A method of making buttons comprising placing a plastic blank within a die, forming recesses from one side through the blank and ending in protuberances on the other side of the blank in alignment with said recesses and having walls which are thinnest where the protuberances join the body of the blank, and breaking the thin walls of the protuberances to form ,thread holes.

WILLIAM M. DAVIDSON.

THOMAS B. JONES. 

